There are known illumination assemblies in the medical diagnostic field, such as the 78010 illuminator assembly manufactured by Welch Allyn Inc., in which a miniature halogen or other miniature incandescent lamp is retained within the confines of a lamp housing. The lamp housing is threaded or otherwise disposed into the distal end of a assembly receptacle or assemblage containing a number of electrical contacts and having a proximal end with a strain relief and a cord containing electrical connectors extending to a power supply, such as a transformer. The assembly receptacle, including the lamp housing, can be implanted into the confines of a handle of a disposable vaginal speculum, such as those described in U.S. Pat. No. 3,176,047, the speculum being equipped with a light conducting end that is configured in order to direct light from the miniature contained halogen bulb to permit conduction of pelvic examinations.
During use in the vaginal speculum, the above described illumination assembly is subsequently exposed to fluids, requiring that the lamp be cleaned and sterilized following use or that the life of the lamp is shortened prematurely due to the presence of fluids entering the housing and corrupting the electrical leads and lamp contacts. To date, there has not been provided an effective technique for providing a fluid-tight seal for a lamp in an illumination assembly such as those described above.
Referring to FIG. 1, and in the assembly of a typical lamp housing, cement, epoxy or other suitable applied adhesive 202 is added into secure the position of the miniature incandescent lamp 200 within the lamp housing 204 as the electrical leads 212 of the lamp are drawn through the bottom of the lamp housing for attachment to the remainder of the illuminator assemblage and more particularly to a contact 216. It is essential during this process that the distal end 220 of the lamp 200 be maintained properly at the distal end 224 of the lamp housing 200. Without the adhesive 202, the lamp 200 would not hold its desired position within the housing when the leads 212 are drawn to the contact 216.
The preceding manufacturing process fails to provide a fluid-tight seal for the lamp housing in that moisture migrates through microfissures that are formed in the adhesive and as readily apparent fails to provide any form of protection for the lamp itself as fluids can easily permeate the boundary between the envelope of the bulb and the interior of the housing.